Scored metal can



Sept. 5, 1967 R. J. STOLLE ET AL 3,339,789

SCORED METAL CAN Filed June 14, 1965 Flg. 3 a

J INVENTORS I gALpuzrouz AND LTON AM/NSK/ AND F 1g. 4 17a fkeDE/EICK J C1055,

ATTOQNEYS.

United States Patent 3,339,789 SCORED METAL CAN Ralph J. Stolle, Lebanon, and Elton G. Kaminski, Sidney, Ohio, and Frederick J. Close, Pittsburgh, Pa., assignors toi (Tillie Stolle Corporation, Sidney, Ohio, a corporation 0 1o Filed June 14, 1965, Ser. No. 463,499

7 Claims. (Cl. 220-54) This invention relates to a scored metal can end and a method of manufacturing the same.

Metal cans have generally been made either as threepiece cans or two-piece cans. In the three-piece can, the can body is made from sheet metal and two separate end members are provided which are then secured to the body to complete the can. More recently cans have been made in the two-piece form wherein the can body and one can end are integral and a separate end is later attached to the open end of the piece having the body with one integral end.

Two-piece cans may be made in several ways. One of these is the so-called wall iron process wherein a shallow cup is produced from sheet metal by conventional drawing techniques and is then redrawn to a cup of longer length and smaller diameter and the redrawn cup is then wall ironed to produce the required body length and wall thickness.

A second way of forming a can body with an integral end is the so-called impact and iron forming process wherein a short cup of proper diameter but with a heavy wall thickness is formed by the so-called impact-extrusion-forming process. The impact extruded short cup is then pushed through ironing dies to reduce the wall thick ness and increase the length of the cup to the required length for trimming and flanging operations.

A third way of producing a can body with an integral end is the so-called impact-extrusion-forming process wherein a metal disc or slug is extruded into a die in an impact-extrusion-forming apparatus under tremendous pressure. In this process the entire forming operation is completed almost instantaneously and no further ironing of the wall is necessary.

Where a can is formed by the impact-eXtrusion-forming process or by the impact and iron forming process, and to a lesser degree even when it is formed by the draw and wall iron process, the wall thickness in the end is not uniform. This is particularly true where the can end instead of being flat is concave. This creates a problem in providing a score line to define an area which was torn out by means of a tab, in that the score line will tear easily in thin portions of the end wall and will not tear easily in thicker portions thereof.

With the foregoing considerations in mind, one of the principal objects of the present invention is to provide a can end, whether it be a separate end or one integral with the can body, having a score line leaving a substantially uniform thickness of metal to be torn during the opening operation. Another object of the invention involves the scoring of the can end prior to the application of any lacquer or enamel so as to eliminate the necessity for over-coating or repair coating. This can be done regardless of the technique by which the can end is formed and regardless of whether the can end is formed separately or integrally with the can body.

Another object of the invention is to provide a can body with an integral end or what is known as a two-piece can, wherein the integral end is provided with the scoring and with the pull tab. This has the advantage in that a simple plain can end is all that is required to complete the package.

These and other objects of the invention which will be 3,339,789 Patented Sept. 5, 1967 described in more detail hereinafter are accomplished by that certain construction and arrangement of parts of which the following is an exemplary embodiment.

Reference is made to the drawings forming a part hereof and in which:

FIG. 1 is a plan view of a can end which may or may not be integral with a body and having a score line defining a portion to be torn out by means of a tab and a rivet for the securing of the tab.

FIG. 2 is a diametrical cross sectional view of a can end similar to FIG. 1, wherein the can end is integral with the can body.

' FIG. 3 is a fragmentary cross sectional view on a greatly enlarged scale taken on the line 4-4 of FIG. 1 after the coining operation and before the scoring operation; and

FIG. 4 is a view similar to FIG. 3 but after the scoring operation has been performed. It is to be understood that the views of FIGS. 3 and 4 are applicable to either a separate can end or an integral can end and that a separate can end would have substantially the same cross section al appearance as the integral can end of FIG. 2..

Briefly, in the practice of the invention, and regardless of the method of forming the can end and whether the can end is integral with a body or not, the can end will gen erally not be of absolutely uniform thickness so that when a score line is formed in such a can end, heavier sections will remain to be torn in some portions of the score line than in others. According to the present invention, the can end is subjected to a coining operation wherein, by means of a coin press, a fiat bottomed groove is formed where the score line will later be formed. As a result of this precoining operation, the depth of metal below the bottom of the groove will be uniform and a score line can thereafter be formed in the groove and the area to be torn out may then be torn out without difficulty. As pointed out above, this precoining and scoring operation can be performed equally well on a separate can end or on an integral can end and it is performed in the manufacture of the end prior to lacquering or coating, so that the scoring operation does not penetrate the lacquer or enamel coating to expose raw aluminum which would necessitate over-coating or repair coating.

Referring in more detail to the drawings, a can end is generally indicated at 11. In most cases the can end will have an annular ridge or bead 12. A rivet member 13 will be provided integral with the can end to which, at a later stage of the operation, a pull tab will be assembled and staked in place.

If the can end, whether it be integral or separate from the can body, has been formed by the impact-extrusionforming process or by the impact and iron forming process, the rivet 13 will be produced during the impact extrusion. If the can end has been formed by the draw and wall iron process, the rivet will be formed in the usual manner by a prebubble operation followed by a rivet forming operation.

Regardless of how the can end and integral rivet have been formed, the end or the can body with an integral end is placed in a coin press and a flat bottomed groove 15 is formed therein, as seen in FIG. 3, in the area where the score line is later to be formed. As a result of this coining operation, the thickness of the can end 11 between the bottom of the groove 15 and the inside surface 11a of the can end can be controlled.

Thereafter a score line 14 is formed in the bottom of the groove 15 as best seen in FIG. 4. As a result of the fact that the distance between the bottom of the groove 15 and the inside surface 11a of the can is substantially constant, the material to be torn in opening a can between the bottom of the score line 14 and the inside surface 11a of the can end 11 will be substantially uniform and the area of the can end within the score line and which is indicated in FIG. 1 at 16 can easily be torn out of the can end 11.

It will be understood that if the can end is concave the configuration of the coining dies will be such as to conform to the general curvature of the can end.

It will also be understood that it is only necessary to coin the fiat bottomed groove 15 to such a depth that nowhere in the groove will the remaining metal between the bottom of the groove 15 and the inside surface 11a be thicker than the thinnest portion of the can end in the region where the score line is to be formed. In other words, the coining need be carried on only such that a slight impression is achieved in the thinnest area of the can end. In this way a substantial thickness of metal will be left between the bottom of the groove 15 and the inside surface 11a in which the score line can be formed. The score line will of course preferably be disposed substantially medially of the groove 15.

Regardless of whether the rivet in the can end has been formed during the impact-extrusion-for-ming process or during the impact portion of the impact and iron forming process, or by the prebubble and forming process in a can which has been subjected to drawing and wall ironing, the tab (shown in broken lines at 17) is then positioned over the rivet 13 and staked in place.

It should be noted that while it is presently conventional practice in the manufacture of so-called easyopen ends to completely finish the ends including lacquering or enameling before scoring and tabbing, one of the problems encountered has been that the scoring frequently penetrates or destroys the lacquer or enamel coating, exposing raw aluminum which, in most cases, requires the application of an over-coat or repair coat to prevent contact between the raw aluminum and the product contained in the can. The present invention overcomes this difficulty in that the scoring and tabbing operation is conducted prior to any lacquering or enameling of the can body or ends.

It should also be noted that while the invention is applicable to separate can ends, its greatest virtue resides in the fact that the easy-open feature can be incorporated in a can end which is integral with the can body. This of course means that the loose end which completes the package does not have to have the easyopen scoring and tab arrangement.

It will be understood that numerous modifications may be made without departing from the spirit of the invention and therefore no limitation not expressly set forth in the claims is intended or should be implied,

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A metal can end having a score line defining an area adapted to be torn out by means of a pull tab, said score line lying substantially centrally in a fiat bottomed groove, the thickness of said can end in said fiat bottomed groove being substantially uniform, whereby the amount of metal remaining under said score line is of substantial uniform thickness for easy removal of said area by tearing.

2. The structure of claim 1, wherein said score line is disposed substantially medially of said flat bottomed groove.

3. Ametal can for beverages and the like, having an integral end and constituting one piece of a two-piece can, said integral end having a score line defining an area thereof adapted to be torn out by means of a pull tab, said score line lying substantially centrally in a flat bottomed groove, the thickness of said can end in said fiat bottomed groove being substantially uniform, whereby the amount of metal remaining under said score line is of substantially uniform thickness for easy removal of said area by tearing.

4. A metal can end having a fiat bottomed groove defining an area adapted to be torn out by means of a pull tab, said groove providing at its bottom a substantially uniform thickness of said end throughout the extent of said groove and a score line in the bottom of said groove coextensive with the length of said groove.

5. The structure of claim 4, wherein said score line is disposed substantially medially of said fiat bottomed groove.

6. A metal can for beverages and the like, having an integral end, a fiat bottomed groove in said end defining an area adapted to be torn out by means of a pull tab, said groove providing at its bottom a substantially uniform thickness of said end throughout the extent of said groove and a score line in the bottom of said groove coextensive with the length of said groove.

7. A metal can according to claim 6, wherein said score line is disposed substantially medially of said flat bottomed groove.

References Cited UNITED STATES PATENTS 3,250,426 5/1966 Fraze 22054 THERON E. CONDON, Primary Examiner.

G. T. HALL, Assistant Examiner,

Disclaimer 3.339,789.Ralph J. StoZIe, Lebanon, Elton G. [famine/ea", Sidney, Ohio, and F rederiek J. Close, Pittsburgh, Pa. SCORED METAL CAN. Patent, dated Sept. 5, 1967. Disclaimer filed Nov. 12, 1971, by the assignee, The Stolle Harpomte'on. Hereby enters this disclaimer to claims 1 through 7 of said patent.

[Oflica'al Gazette September 4, 1973.] 

1. A METAL CAN END HAVING A SCORE LINE DEFINING AN AREA ADAPTED TO BE TORN OUT BY MEANS OF A PULL TAB, SAID SCORE LINE LYING SUBSTANTIALLY CENTRALLY IN A FLAT BOTTOMED GROOVE, THE THICKNESS OF SAID CAN END IN SAID FLAT BOTTOMED GROOVE BEING SUBSTANTIALLY UNIFORM, WHEREBY THE AMOUNT OF METAL REMAINING UNDER SAID SCORE LINE IS OF SUBSTANTIAL UNIFORM THICKNESS FOR EASY REMOVAL OF SAID AREA BY TEARING. 